Electronic apparatus and image capture apparatus capable of detecting halation, method of controlling electronic apparatus, method of controlling image capture apparatus, and storage medium

ABSTRACT

An electronic apparatus that can enhance the accuracy of detection of halation by taking into account the influence of halation on visibility of an object, and also effectively suppress the influence of halation independently of the type of a light source. An evaluation unit evaluates the luminance of the object based on an exposure level at which image data of the object is acquired. A detection unit detects t halation based on the luminance of the object, a first luminance area having a higher luminance than a first luminance threshold value, and a distribution status of another luminance area which is an area having a lower luminance than the first luminance area and is distributed around the first luminance area.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an electronic apparatus that detectshalation, a method of controlling the electronic apparatus, an imagecapture apparatus and an electronic apparatus that perform control forsuppressing the influence of halation, a method of controlling the imagecapture apparatus, and a storage medium.

Description of the Related Art

In a case where an object is photographed with a camera under alow-illuminance (low-luminance) environment, when high-illuminance lightenters the camera, there occurs a phenomenon of halation in which theobject is photographed in a state in which light leaks around thephotographing position of the source of the high-illuminance light. Thehalation occurs when high-luminance incident light forms an image on animage capture device, causing excessive electrical charges to begenerated on the image capture device and propagate to surroundingpixels. An image with halation has a problem of degradation of its imagequality, such as reduced visibility of the object. For example, in acase where an object is photographed at night with a camera for publicroad surveillance, halation sometimes occurs in a captured image. Atnight, the headlights of a vehicle are on, so that a large contrast isgenerated between ambient light around the headlights and the light ofthe headlights. If an object is photographed in this state, an imagewith halation around the headlights of the vehicle is obtained. In theimage with halation, the visibility of the appearance, license platenumber, etc. of the vehicle is reduced.

As the related art, there has been proposed a technique in which whenhalation occurs, an incident light amount is reduced using an electronicshutter generally provided in a CCD camera (see e.g. Japanese Laid-OpenPatent Publication (Kokai) No. 2004-072415). Japanese Laid-Open PatentPublication (Kokai) No. 2004-072415 also discloses that light amountadjusting means formed by a liquid crystal panel is provided forward ofa lens of the camera, for masking excessive incident light, whereby thelight amount is adjusted.

For example, in Japanese Laid-Open Patent Publication (Kokai) No.2004-072415, to eliminate the influence of halation, the incident lightamount is reduced by changing the speed of the electronic shutter to ahigh-speed value. Alternatively, to eliminate the influence of halation,it is also possible to reduce the incident light amount by providing theliquid crystal panel forward of the lens of the camera. Here, even whenhalation has occurred in an image obtained by photographing with thecamera, there is a case where the influence of halation on thevisibility of the image is small. For example, even when halation causedby vehicle headlights has occurred in the image, there is a case wherethe influence of halation on the visibility of a vehicle license plateis small.

On the other hand, in an image obtained by reducing the incident lightamount by controlling the electronic shutter or providing the liquidcrystal panel, image quality of the image is degraded due to decrease inthe incident light amount. Therefore, when the incident light amount isreduced with a view to eliminate the influence of halation, the imagequality of the image is degraded although the influence of halation onthe visibility of the object is low.

As the related art, there has been also proposed a technique forcontrolling insertion/removal of an infrared cut filter and a visiblelight cut filter (see e.g. Japanese Laid-Open Patent Publication (Kokai)No. 2016-220002).

For example, halogen lights that emit light containing a large amount oflight in an infrared wavelength range are often used as vehicleheadlights. In a case where halogen light is used as a light source,even when the infrared cut filter is inserted into an optical path ofthe camera, the light containing a large amount of the light in theinfrared wavelength range enters the camera. For this reason, in theabove-described situation, it is difficult even for the techniqueproposed in Japanese Laid-Open Patent Publication (Kokai) No.2016-220002 to suppress the influence of halation on an image that isobtained by photographing an object with the camera.

SUMMARY OF THE INVENTION

The present invention provides an electronic apparatus and an imagecapture apparatus that are enhanced in the accuracy of detection ofhalation by taking into account the influence of halation on thevisibility of an object, and methods of controlling the electronicapparatus and the image capture apparatus.

The present invention provides an electronic apparatus and an imagecapture apparatus that effectively suppresses the influence of halationindependently of a type of a light source.

In a first aspect of the present invention, there is provided anelectronic apparatus including at least one processor or circuitconfigured to perform the operations of the following units: anevaluation unit configured to evaluate a luminance of an object based onan exposure level at which image data of the object is acquired, and adetection unit configured to detect halation based on the luminance ofthe object, a first luminance area having a higher luminance than afirst luminance threshold value, and a distribution status of anotherluminance area which is an area having a lower luminance than the firstluminance area and is distributed around the first luminance area.

In a second aspect of the present invention, there is provided anelectronic apparatus that performs communication with an image captureapparatus including an image capture device which receives incidentlight containing infrared wavelength light, the electronic apparatusincluding at least one processor or circuit configured to perform theoperation of a control unit configured to perform, in a case wherehalation having occurred in image data is detected based on luminanceinformation of the image data obtained from the image capture device,control for increasing an irradiation light amount of infrared lightirradiated onto an object.

In a third aspect of the present invention, there is provided an imagecapture apparatus including an image capture device that receivesincident light containing infrared wavelength light, and at least oneprocessor or circuit configured to perform the operation of a controlunit configured to perform, in a case where halation having occurred inimage data is detected based on luminance information of the image dataobtained from the image capture device, control for increasing anirradiation light amount of infrared light irradiated onto the object.

In a fourth aspect of the present invention, there is provided a methodof controlling an electronic apparatus, comprising evaluating aluminance of an object based on an exposure level at which image data ofthe object is acquired, and detecting halation based on the luminance ofthe object, a first luminance area having a higher luminance than afirst luminance threshold value, and a distribution status of anotherluminance area which is an area having a lower luminance than the firstluminance area and is distributed around the first luminance area.

In a fifth aspect of the present invention, there is provided a methodof controlling an image capture apparatus including an image capturedevice that receives incident light containing infrared wavelengthlight, the method comprising performing, in a case where halation havingoccurred in image data is detected based on luminance information of theimage data obtained from the image capture device, control forincreasing an irradiation light amount of infrared light irradiated ontoan object.

In a sixth aspect of the present invention, there is provided anon-transitory computer-readable storage medium storing acomputer-executable program for executing a method of controlling anelectronic apparatus, wherein the method comprises evaluating aluminance of an object based on an exposure level at which image data ofthe object is acquired, and detecting halation based on the luminance ofthe object, a first luminance area having a higher luminance than afirst luminance threshold value, and a distribution status of anotherluminance area which is an area having a lower luminance than the firstluminance area and is distributed around the first luminance area.

In a seventh aspect of the present invention, there is provided anon-transitory computer-readable storage medium storing acomputer-executable program for executing a method of controlling animage capture apparatus including an image capture device that receivesincident light containing infrared wavelength light, wherein the methodcomprises performing, in a case where halation having occurred in imagedata is detected based on luminance information of the image dataobtained from the image capture device, control for increasing anirradiation light amount of infrared light irradiated onto an object.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image capture apparatus according to afirst embodiment of the present invention.

FIG. 2 is a flowchart of a halation detection process in the firstembodiment.

FIG. 3 is a diagram showing an example of luminance gradients andluminance areas.

FIG. 4 is a block diagram of an image capture apparatus according to asecond embodiment of the present invention.

FIG. 5 is a flowchart of a halation detection process in the secondembodiment.

FIGS. 6A and 6B are diagrams showing examples of image data used todistinguish between a stationary body and a moving body.

FIG. 7 is a block diagram of an image capture apparatus according to athird embodiment of the present invention.

FIG. 8 is a block diagram of a photographing section.

FIG. 9 is a flowchart of a process performed in the third embodiment.

FIG. 10 is a flowchart of a determination process for determiningwhether or not halation has occurred.

FIG. 11 is a diagram showing an example of luminance gradients and apixel space.

FIG. 12 is a flowchart of a process performed in a fourth embodiment ofthe present invention.

FIG. 13 is a block diagram of an image capture apparatus according to afifth embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail below withreference to the accompanying drawings showing embodiments thereof. Thecomponent elements in the following embodiments are described only byway of example, and are by no means intended to limit the scope of thepresent invention to them alone.

FIG. 1 is a block diagram of an image capture apparatus 1 according to afirst embodiment of the present invention. The image capture apparatus 1is comprised of a photographic lens 3, an image sensor 4, ananalog-to-digital converter 5, a system controller 6, a memory 7, and astorage medium 8. The following description will be given assuming thatthe image capture apparatus 1 is applied to a camera for public roadsurveillance. The image capture apparatus 1 may be a public roadsurveillance camera for unattended operation. However, the image captureapparatus 1 may be used for a purpose other than the public roadsurveillance. Further, although the description is given assuming thatthe image capture apparatus 1 performs moving image photographing, theimage capture apparatus 1 may perform still image photographing. Theimage capture apparatus 1 detects halation which affects objectvisibility. The object is assumed to be a vehicle license plate, avehicle's appearance or the like. For example, in a case where the imagecapture apparatus 1 performs public road surveillance under a lowilluminance environment e.g. at night, halation sometimes occurs in animage captured by the image capture apparatus 1 by vehicle headlights.However, even when halation has occurred in an image, there is a casewhere a degree of the influence of halation is small. In this case, itis sometimes possible to visually determine a vehicle license platenumber or the like as an object, from the image with halation.Therefore, in the following embodiments, halation is detected by takinginto account the influence of halation on the object visibility.

The image capture apparatus 1 includes the photographic lens 3 whichrepresents an optical lens group as an image capture optical system forcapturing an optical image of an object. The image sensor 4 receivesincident light having passed through the image capture optical system.The image sensor 4 photoelectrically converts the received incidentlight and forms an object image as an optical image. The image sensor 4outputs analog electrical signals (analog captured image signals)generated by photoelectrically converting the optical image, to theanalog-to-digital converter 5. The analog-to-digital converter 5converts the analog electrical signals to digital signals (digitalcaptured image signals), and outputs the digital signals to the systemcontroller 6. The system controller 6 includes an image processor 10 andan exposure controller 16. The image processor 10 performs various imageprocessing processes on the digital captured image signals input to thesystem controller 6 to generate image data. Thus, image data isacquired. The exposure controller 16 determines the brightness of theimage data generated by an image generation section 11 of the imageprocessor 10, and controls one of an electronic shutter, an aperture,and a gain of the image sensor 4. This corrects the brightness of theimage data.

The photographic lens 3 is assumed to include a magnification lens thatmoves in an optical axis direction to change the focal length, and afocus lens that moves in the optical axis direction to perform focusing.The image sensor 4 uses a solid-state image capture device (CCD). Theimage capture apparatus 1 can be applied to a color camera or amonochrome camera. In a case where the image capture apparatus 1 is acolor camera, a color filter is disposed at a location closer to anopening of the image capture apparatus 1 than the image sensor 4. Theexposure controller 16 as an exposure control unit has an automaticexposure control function, and sends a command for adjusting thebrightness of an image to the image sensor 4 based on image datagenerated by the image generation section 11. Since this controls anexposure level, the brightness of an image captured by the image captureapparatus 1 is adjusted.

The system controller 6 performs various control processes. The memory 7is e.g. a RAM. The storage medium 8 is e.g. a ROM. The system controller6 may be realized by a CPU that loads control programs stored in thestorage medium 8 into the memory 7 and executes the loaded controlprograms. In the case of the configuration shown in FIG. 1, the imagecapture apparatus 1 including the image sensor 4 and the systemcontroller 6 corresponds to an electronic apparatus. The systemcontroller 6 may be provided as a separate external controller (e.g. apersonal computer) from the image capture apparatus 1. In this case, theexternal controller functioning as the system controller 6 performscommunication with the image capture apparatus 1, whereby the processesof the embodiments are realized. In this case, the external controllercorresponds to the electronic apparatus.

The image processor 10 includes the image generation section 11, a firstevaluation section 12, a second evaluation section 13, a halationevaluation section 14, and a threshold value determination section 15.The image generation section 11 generates image data based on digitalcaptured image signals. The first evaluation section 12 evaluates aluminance of the image data to thereby label a blown-out highlight area(first luminance area) and one or a plurality of other luminance areasdistributed around the blown-out highlight area. The first evaluationsection 12 corresponds to a classification unit. The second evaluationsection 13 as an evaluation unit estimates a luminance of an object anda luminance of ambient light from an exposure level to thereby evaluatethe luminance of the object and the luminance of the ambient light. Thehalation evaluation section 14 evaluates, based on the distribution ofthe luminance areas detected by the first evaluation section 12, whetheror not there has occurred halation having a small influence on theobject visibility. The halation having a small influence on the objectvisibility is halation that is not required to be detected. Note that inthe present embodiment, exposure or the brightness of illuminance(luminance) is defined based on an APEX (ADDITIVE SYSTEM OF PHOTOGRAPHICEXPOSURE) system. For example, the difference between 1BV and 2BV of theobject luminance corresponds to a difference of one level in thebrightness of an object illuminance (luminance) in the APEX system.

The halation evaluation section 14 evaluates whether or not halationaffecting the object visibility has occurred, by taking into account notonly the distribution status of high-luminance areas in and around theblown-out highlight area but also the object luminance. The halationaffecting the object visibility is detected according to the result ofthe evaluation by the halation evaluation section 14 as the detectionunit. The threshold value determination section 15 determines apredetermined luminance value used by the second evaluation section 13for evaluating the object luminance, and one or a plurality of luminancethreshold values used by the halation evaluation section 14 forevaluating halation. The threshold value determination section 15 as achange unit changes the luminance threshold value(s) according to theobject luminance evaluated by the second evaluation section 13.

Next, a halation detection process of the first embodiment will bedescribed with reference to FIG. 2. The second evaluation section 13estimates a luminance of an object from an exposure level to therebyevaluate the object luminance (S100). The threshold value determinationsection 15 determines whether or not the object luminance is equal to orhigher than the predetermined luminance value (S101). The predeterminedluminance value can be set to a desired value. If the answer to thequestion of the step S101 is affirmative (YES), the threshold valuedetermination section 15 increases the luminance threshold value(s) foruse in classifying luminance areas in image data (S102), and then theprocess proceeds to a step S103. If the answer to the question of thestep S101 is negative (NO), the process directly proceeds to the stepS103. In the step S103, the first evaluation section 12 detects aplurality of luminance areas from the image data, by using the one orthe plurality of luminance threshold values, and labels the detectedluminance areas. This labeling is processing for classifying theluminance areas of the image data. As mentioned above, if the answer tothe question of the step S101 is affirmative (YES), the threshold valuedetermination section 15 sets the luminance threshold value(s) to ahigher value or higher values. The initial value of each luminancethreshold value may be a desired value. For example, the initial valuesof the luminance threshold values may be luminance threshold values fordetecting halation under a low-illuminance environment, such as atnight, at dawn, or in the evening. If the answer to the question of thestep S101 is affirmative (YES), the threshold value determinationsection 15 changes the luminance threshold value(s) from the initialvalue(s) to a higher value or higher values.

The first evaluation section 12 labels an area having the highestluminance level (luminance equal to or higher than a first luminancethreshold value) as a first luminance area. Then, the first evaluationsection 12 labels, as an n-th area, an area with a luminance which isequal to or higher than an n-th luminance threshold value (n is aninteger of equal to or larger than 2), and also is smaller than an(n−1)-th luminance threshold value, with the first luminance area in thecenter. As the value of “n” becomes larger, the luminance level of then-th area becomes lower. The first luminance area is a blown-outhighlight area, for example.

FIG. 3 is a diagram showing an example of luminance gradients andluminance areas. FIG. 3 shows a case of “n=3”, in which the firstluminance threshold value, a second luminance threshold value, and athird luminance threshold value are used. In FIG. 3, (A) shows arelationship between luminance gradients of the image data and theluminance threshold values, and (B) shows the distributions of theluminance areas (labeled luminance areas) corresponding to (A) of FIG.3. The first luminance area is an area having the highest luminancelevel, i.e. an area with luminance equal to or higher than the firstluminance threshold value. As shown in (B) in FIG. 3, a second luminancearea is distributed concentrically with the first luminance area in thecenter, and a third luminance area is distributed outside the secondluminance area. The halation evaluation section 14 detects halation whenthere are distributed luminance areas in which the luminance becomeslower in an outer peripheral direction, with the first luminance area inthe center, as in (B) in FIG. 3.

Here, if the answer to the question of the step S101 is affirmative(YES), the processing in the step S102 is executed. More specifically,if the object luminance is bright, the threshold value determinationsection 15 increases the luminance threshold value(s). With this, if theobject luminance is bright, the gradation of luminance around theblown-out highlight area is maintained, and the halation evaluationsection 14 ceases to detect halation that is not required to bedetected.

Since halation is liable to occur around the blown-out highlight area,the halation evaluation section 14 extracts the labeled first luminancearea as the blown-out highlight area (S104). By focusing on theluminance distribution status around the blown-out highlight area, thehalation evaluation section 14 performs evaluation of halationdetection. The halation evaluation section 14 determines, according tothe object luminance, a range of reference (scanning) for evaluation ofhalation detection from the first luminance area (blown-out highlightarea) as the center. This is because the degree of influence of halationon the object visibility recognizability varies with a luminance ratiobetween the ambient light and a high-luminance object. As thehigh-luminance object, a white object, such as a vehicle license plate,for example, is assumed.

When a high-luminance object enters the angle of view of the imagecapture apparatus 1, an exposure amount is changed for brightnesscorrection. When a change in the exposure amounts of two successiveframes (image data items) of a moving image captured by the imagecapture apparatus 1 is large, the luminance ratio between the ambientlight and the high-luminance object is also large. In a case where theluminance ratio between the ambient light and the high-luminance objectis large, it is expected that the degree of influence of halation on thevisibility of the object is large. On the other hand, in a case wherethe change in the exposure amounts of two successive frames is small,the luminance ratio between the ambient light and the high-luminanceobject is small. In this case, it is expected that the degree ofinfluence of halation on the visibility of the object is small. Thehalation evaluation section 14 does not detect such a degree of halationas will not affect the object visibility. When halation is detected,control for suppressing the influence of halation on the image data isperformed. For example, in a case where the image capture apparatus 1has an insertion/removal mechanism provided on an optical path of thephotographic lens 3, for inserting and removing a filter (e.g. a visiblelight cut filter) which cuts specific wavelength light, theinsertion/removal mechanism inserts the filter into the optical pathaccording to the detection of halation. This makes it possible tosuppress the influence of halation.

However, when the visible light cut filter is inserted into the opticalpath, light having a visible light component is cut, and hence the imagequality of the image data is reduced. To solve this problem, thehalation evaluation section 14 does not detect such a degree of halationas will not affect the object visibility as halation. This prevents theimage quality of the image data from being reduced by detection ofhalation which is not required to be detected.

Here, in halation detection focusing on luminance gradients around theblown-out highlight area (first luminance area), detection accuracytends to depend on object luminance around the blown-out highlight area.More specifically, irrespective of the degree of influence of halation,when the object luminance around the blown-out highlight area is high,the object luminance around the blown-out highlight area is detected asluminance caused by flare. Therefore, the halation detection focusingsimply on the luminance gradients around the blown-out highlight areahas low reliability. To cope with this, the halation evaluation section14 determines whether or not the luminance ratio between the ambientlight and the high-luminance object is equal to or lower than apredetermined value (S105). As described above, the luminance ratiobetween the ambient light and the high-luminance object is acquiredbased on a change in the exposure amounts of two successive frames. Forexample, the luminance ratio between the ambient light and thehigh-luminance object is acquired based on a value obtained bydifferentiating the change in the exposure amounts of two successiveframes with respect to time. If the answer to the question of the stepS105 is affirmative (YES), the luminance ratio between the ambient lightand the high-luminance object is small. In this case, the halationevaluation section 14 expands the reference range for detecting halation(S106). For example, the halation evaluation section 14 expands thereference range for detecting halation not only to the first and secondluminance areas but also to the third luminance area. With this, evenwhen the luminance ratio between the ambient light and thehigh-luminance object is small, it is possible to improve thereliability of the halation detection. On the other hand, if the answerto the question of the step S105 is negative (NO), the process proceedsto a step S107, and in this case, the halation evaluation section 14 maycontinue setting the reference luminance area for detecting halatione.g. to the first luminance area and the second luminance area.

The halation evaluation section 14 determines whether or not an n-thluminance area smaller in luminance than an (n−1)-th luminance area isdistributed in the outer peripheral direction within the reference range(S107). That is, the halation evaluation section 14 performs halationdetermination by evaluating that there are distributed luminance areasin which the luminance level becomes lower from the first luminance areain the outer peripheral direction, as shown in FIG. 3. If the answer tothe question of the step S107 is affirmative (YES), the halationevaluation section 14 detects halation (S108). On the other hand, if theanswer to the question of the step S107 is negative (NO), the processreturns to the step S100. In this case, halation is not detected. Thatis, halation having a small influence on the object visibility (halationwhich is not required to be detected) is not detected. The halationdetection process in the first embodiment is performed, as describedabove.

In a case where halation is detected based on the first luminance areaand the other luminance areas (luminance areas distributed around thefirst luminance area), halation having a small influence on the objectvisibility is also detected. However, the system controller 6 of thepresent embodiment evaluates the object luminance based on an exposurelevel at which the image data was acquired. Then, the system controller6 detects halation based on the object luminance, the first luminancearea, and other luminance areas. This suppresses the detection ofhalation which has a small influence on the object visibility and is notrequired to be detected.

If the answer to the question of the step S101 is affirmative (YES), theobject luminance is bright. When the object luminance is bright, it isassumed that the degree of influence of halation caused by vehicleheadlights and the like on the object visibility is small. In this case,the threshold value determination section 15 increases the luminancethreshold value(s) for labeling the luminance areas. As a consequence,when the object luminance is bright, the luminance levels of theluminance areas used for the determination in the step S107 becomeshigher. In this case, the distributions of the luminance areas, as shownin FIG. 3, cease to be detected. Therefore, the halation evaluationsection 14 ceases to detect halation which is not required to bedetected.

As described above, the halation evaluation section 14 detects halationthat affects object visibility based on whether or not the n-th areaexists which indicates that the luminance becomes lower in the outerperipheral direction, with the first luminance area in the center. Thehalation evaluation section 14 may detect halation that affects theobject visibility by a method other than the method described above. Forexample, the halation evaluation section 14 may detect halation bysetting the first luminance area as the blown-out highlight area and aluminance area other than the first luminance area as a flare area, andevaluating an area ratio between the blown-out highlight area and theflare area.

Next, a description will be given of a second embodiment of the presentinvention. Halation is liable to occur when the luminance ratio betweenthe ambient light and the high-luminance object is large. For example,halation often occurs at night, etc. In a case where the image captureapparatus 1 is applied to a camera or the like for performing publicroad surveillance, there can occur not only halation caused by vehicleheadlights but also halation caused by light of a street lamp in imagedata of an image captured by the image capture apparatus 1. An imagecapture apparatus 2 according to the second embodiment excludes light ofa stationary body, such as a street lamp, from targets from whichhalation is to be detected. FIG. 4 is a block diagram of the imagecapture apparatus 2 according to the second embodiment. The imagecapture apparatus 2 according to the second embodiment is different fromthe image capture apparatus 1 according to the first embodiment shown inFIG. 1 in that the image capture apparatus 2 further includes aband-pass filter 9, a moving body detection section 17, an infraredillumination controller 18, an infrared illumination unit 20, and atimer 21. The other components of the image capture apparatus 2according to the second embodiment are configured similar to those ofthe image capture apparatus 1 according to the first embodiment, andhence description thereof is omitted.

The band-pass filter 9 is disposed such that it can be inserted andremoved between the photographic lens 3 and the image sensor 4. Theband-pass filter 9 cuts light in a specific wavelength range. Theband-pass filter 9 is inserted into and removed from an optical path ofincident light from the photographic lens 3 by a predeterminedinsertion/removal mechanism. The infrared illumination controller 18performs control for causing infrared light to be irradiated from theinfrared illumination unit 20. The timer 21 counts time, and when apredetermined time period has elapsed, notifies the system controller 6of the fact.

The band-pass filter 9 is assumed to include an infrared cut filter forcutting infrared light and a visible light cut filter for cuttingvisible light. For example, in a case where the halation evaluationsection 14 has detected occurrence of halation, with a view to restoringobject visibility, the above-mentioned predetermined insertion/removalmechanism inserts the visible light cut filter of the band-pass filter 9into the optical path of incident light from the photographic lens 3.Then, the predetermined insertion/removal mechanism removes the infraredcut filter of the band-pass filter 9 from the optical path of incidentlight incident from the photographic lens 3. This reduces the degree ofinfluence of halation. The insertion/removal of the band-pass filter 9is controlled by the system controller 6, for example. In a case wherethe system controller 6 performs control for inserting the visible lightcut filter into the optical path of incident light, the infraredillumination controller 18 causes infrared light to be irradiated fromthe infrared illumination unit 20. In doing this, the infraredillumination controller 18 controls the infrared illumination unit 20such that infrared light having higher illuminance than light of thereduced halation is irradiated. With this control, brightness of imagedata acquired by the image capture apparatus 2 is ensured, and thehalation is more reduced.

The memory 7 temporarily stores image data generated by the imagegeneration section 11. When the system controller 6 receives thenotification notifying the lapse of the predetermined time period fromthe timer 21, the image processor 10 updates a reference image forbackground subtraction in movement detection to image data acquired atthe time of receiving the notification. In the second embodiment, theimage capture apparatus 2 distinguishes between halation caused by astationary body and halation caused by a moving body, and narrows thetargets from which halation is to be detected to the moving body. Thestationary body corresponds to a physical object that does not move. Themoving body corresponds to a physical object that moves.

Next, a halation detection process of the second embodiment will bedescribed with reference to FIG. 5. The FIG. 5 flowchart is formed byadding steps of S207, S208, S209, and S212 to the FIG. 2 flowchart ofthe first embodiment. Since steps S200 to S206, S210, and S211 otherthan the steps of S207, S208, S209, and S212 are the same as those ofthe FIG. 2 flowchart, description thereof is omitted. The moving bodydetection section 17 performs movement detection by backgroundsubtraction, and determines whether or not there is a moving body, basedon a difference from the reference image in the background subtraction(S207). FIGS. 6A and 6B are diagrams showing respective examples of thereference image and image data acquired when a time t has elapsed. FIG.6A shows the reference image (image data used as a reference), and FIG.6B shows the image data (frame t) acquired when the time t has elapsed.The image data is divided into a plurality of lattice-shaped areas, andboth of the image data items of the reference image and the frame tcontain an area S which is the blown-out highlight area (first luminancearea). Since the area S is contained in both of the image data items ofthe reference image and the frame t, and hence it is possible todetermine that the area S is a stationary body, such as a street lamp.

On the other hand, an area M, which is the blown-out highlight area ofthe frame t, is contained in the image data of the frame t, but is notcontained in the reference image. Therefore, the area M can bedetermined to be a moving body, such as a vehicle. As describedhereinabove, based on a binary image using the first threshold value, itis possible to determine whether or not there is a moving body. If theanswer to the question of the step S207 is affirmative (YES), sincethere is a moving body, the process proceeds to a step S210. Thus, thehalation evaluation section 14 can narrow the targets from whichhalation affecting the object visibility is to be detected to a movingbody. As described above, the stationary body is excluded from thetargets for detecting halation that affects the object visibility.

If the answer to the question of the step S207 is negative (NO), thesystem controller 6 determines whether or not the predetermined timeperiod has elapsed (S208). When the predetermined time period haselapsed, the timer 21 notifies the system controller 6 of the fact.Therefore, as long as the system controller 6 does not receive thenotification from the timer 21, the answer to the question of the stepS208 is negative (NO). If the answer to the question of the step S208 isnegative (NO), the process returns to the step S200. If the answer tothe question of the step S208 is affirmative (YES), since it isdetermined that the predetermined time period has elapsed, and also thatthere is no moving body, the image processor 10 updates the referenceimage (S209). With this, it is possible to update the reference image tothe latest image data every predetermined time period.

As shown in FIG. 5, when halation is detected in the step S211, thesystem controller 6 performs an image improvement process on image dataacquired after detection of the halation (S212). For example, theexposure controller 16 may improve the image quality of the image dataacquired after detection of the halation by executing exposure control,such as wide dynamic range processing (WDR processing). Further, thesystem controller 6 may perform control for causing the predeterminedinsertion/removal mechanism to insert the visible light cut filter ofthe band-pass filter 9 into the optical path of incident light. Thisreduces the halation to thereby improve the image quality of the imagedata acquired after detection of the halation. The processing in thestep S212 may be executed in the first embodiment.

Next, a description will be given of a third embodiment of the presentinvention. FIG. 7 is a block diagram of an image capture apparatus 100according to the third embodiment. The image capture apparatus 100 iscomprised of a photographing section 101, an auxiliary storage device102, an illumination section 103, a controller 104, a data communicationsection 105, and a display section 106. The following description willbe given assuming that the image capture apparatus 100 is applied to acamera for public road surveillance. The image capture apparatus 100 maybe a public road surveillance camera for unattended operation. However,the image capture apparatus 100 may be used for a purpose other than thepublic road surveillance. Further, although the description is givenassuming that the image capture apparatus 100 performs moving imagephotographing, the image capture apparatus 100 may perform still imagephotographing. In a case where the image capture apparatus 100 isapplied to the camera for public road surveillance, a vehicle'sappearance, a vehicle license plate, or the like is assumed as anobject. For example, in a case where the image capture apparatus 100performs public road surveillance under a low illuminance (luminance)environment e.g. at night, vehicle headlights each using halogen lightas a light source sometimes causes halation in an image obtained byphotographing an object using the image capture apparatus 100. If theimage is affected by the halation caused by the vehicle headlights, thevisibility of the vehicle's appearance, the vehicle license plate, orthe like is reduced, whereby it becomes difficult to determine thevehicle's appearance, the vehicle license plate, or the like from theimage. Hereinafter, a description will be given of an example in whichthe image capture apparatus 100 suppresses occurrence of halation in animage by controlling the irradiation amount of illumination light havingan infrared wavelength. Note that the image capture apparatus 100 may beapplied to an image capture apparatus other than the camera for publicroad surveillance.

Although in the example shown in FIG. 7, the image capture apparatus 100includes the illumination section 103, the controller 104, and thedisplay section 106, the illumination section 103, the controller 104,and the display section 106 may be provided as devices separate from theimage capture apparatus 100. For example, the illumination section 103may be an external illumination device connected to the image captureapparatus 100. Further, the display section 106 may be an externaldisplay device which is wiredly or wirelessly connected to the datacommunication section 105 of the image capture apparatus 100. Further,the controller 104 as well may be provided as an external device (e.g. apersonal computer) separate from the image capture apparatus 100. Inthis case, the external device (electronic device) having the functionsof the controller 104 communicates with the image capture apparatus 100to thereby perform various control processes of the present embodiment.

FIG. 8 is a block diagram of the photographing section 101. Thephotographing section 101 operates under the control of the controller104. The photographing section 101 is comprised of a zoom lens 201, afocus lens 202, a diaphragm unit 203, an optical filter 204, an imagecapture device 205, an AGC 206, and an analog-to-digital converter 207.Further, the photographing section 101 includes a camera signalprocessor 208, a camera signal transmission section 209, a zoom drivesection 210, a focus drive section 211, and an image capture controller212. In FIG. 8, arrows each indicated by a dotted line represent light,and arrows each indicated by a solid line represent signal lines. Whenincident light from a photographing target enters the photographingsection 101, the photographing section 101 converts the incident lightto digital signals for output. The image capture controller 212 controlsthe camera signal processor 208, the zoom drive section 210, and thefocus drive section 211.

The zoom drive section 210 performs optical enlargement and reductioncontrol of incident light by moving the zoom lens 201 back and forth onthe image capture optical path. The focus drive section 211 performsfocusing control of incident light by moving the focus lens 202 back andforth on the image capture optical path. The exposure amount of lighthaving passed through the zoom lens 201 and the focus lens 202 isadjusted by the diaphragm unit 203. The light whose exposure amount hasbeen adjusted by the diaphragm unit 203 passes through the opticalfilter 204. The light having passed through the optical filter 204 iscaptured as an image by the image capture device 205. In the presentembodiment, the optical filter 204 is described assuming that it is avisible light cut filter for cutting light in the wavelength range ofvisible light. In this case, light entering the image capture device 205is infrared wavelength light. However, the optical filter 204 is notlimited to the visible light cut filter. For example, the optical filter204 may be made of dummy glass that transmits light in all wavelengthranges. Further, the optical filter 204 can be inserted into and removedfrom the image capture optical path. In this case, the predeterminedinsertion/removal mechanism controls the insertion/removal of theoptical filter 204 into/from the image capture optical path. Forexample, the optical filter 204 may be an IR cut filter for cuttinginfrared wavelength light. In this case, the insertion/removal mechanismremoves the IR cut filter as the optical filter 204 from the imagecapture optical path.

Light captured as an image by the image capture device 205 is convertedto analog signals, and the analog signals are electrically amplified bythe AGC (auto gain control) 206. The analog-to-digital converter 207converts the amplified analog signals to digital signals. The camerasignal processor 208 performs development processing, such asdemosaicing, on the digital signals output by the analog-to-digitalconverter 207. Thus, a digital image is formed. The camera signaltransmission section 209 transmits the formed digital image to theauxiliary storage device 102 or an external device.

The auxiliary storage device 102 stores the above-mentioned digitalimage, various evaluation values indicative of the internal states ofthe photographing section 101, commands from the controller 104, and soforth. The various evaluation values indicate the respective states ofthe zoom lens 201, the focus lens 202, the diaphragm unit 203, and theoptical filter 204. Information stored in the auxiliary storage device102 may be stored in a RAM 112 of the controller 104. Further, thecommands from the controller 104 include commands for image qualitycorrection, detection processing with respect an object, and so forth.In the present embodiment, the image quality correction refers to imagequality correction processing for improving the image quality of anobject, such as processing for changing a γ curve according to the stateof a luminance histogram, and processing for changing saturationaccording to an estimated EV value. As the processing for changing the γcurve, for example, in a case where the luminance histogram is biasedtoward low luminance at a predetermined ratio, it is possible to applyprocessing for shifting the γ curve toward high luminance. As theprocessing for changing the saturation according to the estimated EVvalue, in a case where the estimated EV value is lower than apredetermined value, it is possible to apply processing for reducing thesaturation. The EV value corresponds to a value that serves as an indexof brightness. On the other hand, the detection processing is processingfor detecting at least a halation phenomenon. When the illuminance of animage capture environment under which an image is captured by thephotographing section 101 is low (when the illuminance is equal to orlower than a predetermined illuminance), or when the controller 104 hasdetected halation, the amount of irradiation light (irradiation lightamount) is increased under the control of the controller 104.Hereinafter, the illumination section 103 is described assuming that itirradiates infrared light.

The controller 104 appearing in FIG. 7 performs various processingprocesses. The controller 104 is comprised of a CPU 111, the RAM 112,and a ROM 113. The functions of the controller 104 may be realized bythe CPU 111 that loads control programs stored in the ROM 113 into theRAM 112, and executes the control programs loaded into the RAM 112. Inthe present embodiment, when the controller 104 detects halation byreferring to image data temporarily stored in the auxiliary storagedevice 102, the controller 104 controls the irradiation light amount ofthe illumination section 103. Further, the controller 104 estimates anEV value of the image capture environment by evaluating the state of thephotographing section 101 and the image data temporarily stored in theauxiliary storage device 102, and controls the exposure amount of thephotographing section 101 based on estimation results. Further, thecontroller 104 performs image quality correction of an image temporarilystored in the auxiliary storage device 102. Upon input of the image dataoutput from the auxiliary storage device 102, the data communicationsection 105 transmits the input image data to the display section 106.For example, in a case where the display section 106 is not incorporatedin the image capture apparatus 100 but is provided outside the imagecapture apparatus 100, the data communication section 105 performs wiredor wireless communication between the auxiliary storage device 102 andthe display section 106. Upon input of the image data output from thedata communication section 105, the display section 106 displays theimage data. This makes it possible for the display section 106 topresent an image of the object to a user. In a case where the image datainput to the display section 106 has been compressed by the controller104, the display section 106 decompresses the image data beforedisplaying the same.

Next, a process performed in the present embodiment will be describedwith reference to FIG. 9. In the present embodiment, the illuminationsection 103 increases the illuminance of the image capture environmentby irradiating infrared light. As described hereinabove, when the imagecapture apparatus 100 captures an image of an object for public roadsurveillance, the illumination section 103 irradiates near-infraredwavelength light, for example, as infrared light, such that no visualload is imposed on a vehicle driver. First of all, a visible light cutfilter as the optical filter 204 is set on the image capture opticalpath (S301). For example, in a case where the image capture apparatus100 includes an insertion/removal mechanism for inserting/removing thevisible light cut filter, the insertion/removal mechanism inserts thevisible light cut filter as the optical filter 204 into the imagecapture optical path. The visible light cut filter may be set on theimage capture optical path by a desired method. By setting the visiblelight cut filter on the image capture optical path, light entering theimage capture device 205 becomes infrared wavelength light. With this,even when halation has occurred, the degree of influence of halation onimage data is reduced.

The controller 104 sets, in the illumination section 103, a sufficientlight amount enabling image capture with excellent brightness under animage capture environment without halation, as a first light amount, andcauses the illumination section 103 to irradiate infrared light (S302).The photographing section 101 performs photometry of a scene to be shot,by a predetermined photometry method under the control of the controller104 (S303). The user can set the photometry method as desired. Thephotographing section 101 sets a first shutter speed at which correctexposure is achieved (S304). To evaluate the intensity of halation,referred to hereinafter, the controller 104 estimates an EV value of theimage capture environment based on a state of exposure in a scene freefrom halation and luminance information of acquired image data, andstores the EV value in the auxiliary storage device 102 (S305). Notethat in the present embodiment, the exposure and the brightness ofluminance (illuminance) are defined based on the APEX (ADDITIVE SYSTEMOF PHOTOGRAPHIC EXPOSURE) system. For example, the difference between anexposure of 1BV and an exposure of 2BV corresponds to a difference ofone level in the brightness of the exposure in the APEX system. Thecontroller 104 determines whether or not halation has occurred (S306).If the answer to the question of the step S306 is affirmative (YES), itmeans that halation is detected, whereas if the answer to the questionof the step S306 is negative (NO), it means that halation is notdetected.

Next, the determination process for determining whether or not halationhas occurred (S306) will be described with reference to FIG. 10. Thecontroller 104 determines whether or not the estimated EV value is equalto or larger than a predetermined threshold value (S401). Thepredetermined threshold value may be set as desired. For example, thepredetermined threshold value may be a value empirically set in advance.Further, the predetermined threshold value may be a value associatedwith an amount of change from an estimated EV value of the immediatelypreceding acquired image data. For example, when a constant estimated EVvalue continues, the controller 104 may set the constant estimated EVvalue as the predetermined threshold value.

If the answer to the question of the step S401 is affirmative (YES), thecontroller 104 determines whether or not a luminance equal to or higherthan the first luminance threshold value exists in the acquired imagedata (S402). The first luminance threshold value is for filtering ahigh-luminance area, such as the blown-out highlight area. The firstluminance threshold value may be set to a desired value. For example,the first luminance threshold value may be a desired value empiricallyobtained.

If the answer to the question of the step S402 is affirmative (YES),since a high-luminance area (first luminance area) exists in the imagedata, there is a possibility that halation has occurred. In this case,the controller 104 determines whether or not the second luminance areais distributed around the first luminance area (S403). The secondluminance area is an area with a luminance equal to or higher than thesecond luminance threshold value which is lower than the first luminancethreshold value. The luminance equal to or higher than the secondluminance threshold value indicates that it is a luminance of an areaaround the high-luminance area in the halation phenomenon, an image ofwhich is captured due to charge leakage in the image capture device 205.In short, the second luminance threshold value represents a luminanceindicating charge leakage caused by halation. The luminance in thesecond luminance area is lower than the luminance in the first luminancearea. When the second luminance area is distributed in the image data ina manner adjacent to the first luminance area, the answer to thequestion of the step S403 is affirmative (YES). If the answer to thequestion of the step S403 is affirmative (YES), there is a highpossibility of occurrence of halation, and hence the controller 104determines that halation has occurred (S404).

On the other hand, if the answer to the question of any of the stepsS401, S402, and S403 is negative (NO), there is a low possibility ofoccurrence of halation. In this case, the controller 104 determines thathalation has not occurred (S405). Thus, based on the luminanceinformation of the image data, it is determined whether or not halationhas occurred.

FIG. 11 is a diagram showing an example of luminance gradients and apixel space. In FIG. 11, (A) shows luminance gradients in a gradientextraction row appearing in (B), and (B) shows the pixel space of theimage data. In (A) of FIG. 11, a luminance close to the center of theluminance gradients is equal to or higher than the first luminancethreshold value. Therefore, in this case, the answer to the question ofthe step S402 is affirmative (YES). Further, as shown in (B) of FIG. 11,the second luminance area is distributed in the vicinity of the firstluminance area. Therefore, in this case, the answer to the question ofthe step S403 is affirmative (YES). Thus, if the estimated EV value isequal to or higher than the predetermined threshold value, thecontroller 104 determines that halation has occurred.

If it is determined that halation has occurred, by the above-describeddetermination process for determining whether or not halation hasoccurred, the answer to the question of the step S306 in FIG. 9 isaffirmative (YES). In this case, the controller 104 refers to theimmediately preceding image data (immediately preceding frame)temporarily stored in the auxiliary storage device 102. Then, thecontroller 104 detects a moving area by comparing the immediatelypreceding frame and the current frame (acquired image data) which aredifferent in time (S307). Further, the controller 104 evaluates theintensity of the halation (S308). The steps S308 and S309 are forderiving a sufficient irradiation light amount (second light amount) tosuppress halation. In the present embodiment, the controller 104evaluates the intensity of the halation using a difference between thecurrent estimated EV value and an estimated EV value stored in the past,as expressed by the following equation (1):d _(ev) =ev−ev _(pre)  (1)

In the above equation (1), “d_(ev)” represents the difference. “ev”represents the current estimated EV value. “ev_(pre)” represents theestimated EV value stored in the past. The difference “d_(ev)” is anindex of evaluation of the intensity of the halation. The halationintensity may be evaluated by a method other than the above-describedmethod. For example, the halation intensity may be evaluated by an arearatio between the first luminance area and the second luminance areaappearing in FIG. 11.

The controller 104 derives the second light amount for suppressing thehalation according to the evaluated halation intensity, from thefollowing equation (2) (S309):l ₂ =m _(hal){1−exp(−ad _(ev))}(l _(max) −l _(def))+l _(def)  (2)

In the above equation (2), “l₂” represents the second light amount forsuppressing the halation. “m_(hal)” represents a mask parameterindicative of a result of the determination of halation, and takes avalue of 0 or 1. “a” represents an adjustment parameter adjustedaccording to a scene to be shot, and takes a value equal to or largerthan 0. “d_(ev)” is a value indicative of the above-mentioned evaluatedintensity of the halation. “l_(max)” represents a maximum allowableirradiation light amount of the illumination section 103. “l_(def)”represents an irradiation light amount of the illumination section 103obtained when it is not determined that halation has occurred, andcorresponds to the first light amount. The controller 104 sets theabove-mentioned second light amount “l₂” in the illumination section103, to thereby cause the illumination section 103 to irradiate infraredlight with the second light amount “l₂” (S310). The second light amountobtained by the above-mentioned equation (2) is larger than the firstlight amount. Therefore, if it is determined that halation has occurred,the irradiation light amount of the illumination section 103 isincreased.

The image capture controller 212 of the photographing section 101adjusts exposure in accordance with irradiation of light from theillumination section 103. The image capture controller 212 performscontrol for limiting a photometry area to the moving area detected inthe step S307, and performs photometry control to adjust exposure to anobject, (S311). Further, the image capture controller 212 controls ashutter speed, to thereby set a second shutter speed for achieving acorrect exposure of a moving object (S312). By the above processing,image data with suppressed halation is acquired. If the answer to thequestion of the step S306 is affirmative (YES), the steps S307 to S312are executed, whereby the irradiation light amount of the illuminationsection 103 is increased. On the other hand, if the answer to thequestion of the step S306 is negative (NO), since it is determined thathalation has not occurred, the steps S307 to S312 are not executed. Notethat as described hereinabove, in the step S311, the control forlimiting the photometry area to the moving area and the photometrycontrol for adjusting the exposure to the object are performed, but whenthe moving area ceases to be detected, a predetermined photometry methodmay be automatically set. The predetermined photometry method may be oneof central emphasis, overall average, and spot photometry. Further, theuser can set a desired one of the above photometry methods.

After the step S312, or when the answer to the question of the step S306is negative (NO), the controller 104 corrects the image data to improvean image quality thereof (S313). With this, processing of one frame ofimage data is terminated. The data communication section 105 acquiresthe image data (current frame) temporarily stored in the auxiliarystorage device 102, and transmits the image data to the display section106 (S314). The display section 106 displays the current frame (S315).This makes it possible to present the current frame to the user.

For example, when a vehicle headlight using halogen light as a lightsource enters an image acquired by the image capture apparatus 100photographing an object, image data is affected by halation, since thehalogen light contains a large amount of infrared light, differentlyfrom LED. When the image data is affected by the halation, not thevisibility of a headlight area with the halation but the visibilities ofa vehicle appearance area, a vehicle license plate area, and so forthare reduced. This makes it difficult for the user to determine theappearance, license plate number, etc. of the vehicle from the imagedata displayed on the display section 106. To solve this problem, whenit is determined in the step S306 that halation has occurred, thecontroller 104 causes the illumination section 103 to increase theamount of infrared light irradiated therefrom from the first lightamount to the second light amount. With this, even when halation hasoccurred due to reception of a large amount of infrared wavelengthlight, since the amount of the infrared light irradiated from theillumination section 103 is increased, it is possible to suppress theinfluence of halation. Therefore, even if the influence of halation hasoccurred during acquisition of the image data, the visibilities of theappearance, license plate number, etc. of the vehicle of the image datadisplayed on the display section 106 are improved. Thus, it is possibleto suppress the influence of halation which has occurred in the image,independently of the type of the light source. Further, when nooccurrence of halation is detected in the step S306, the amount ofinfrared light is not increased. As a consequence, compared with a casewhere a large amount of infrared light is always irradiated, it ispossible to reduce electric power consumed to irradiate infrared light.

Here, although the luminance of image data is higher when halationoccurs, there is a possibility that an average luminance of the whole orpart of image data is the same between when halation occurs and whenhalation does not occur. In the third embodiment, the controller 104increases the amount of infrared light irradiated from the illuminationsection 103, not based on the average luminance, but when the answer tothe question of the step S306 is affirmative (YES). In other words, whenthe answer to the question of the step S403 in FIG. 10 is affirmative(YES), the controller 104 increases the irradiation light amount ofinfrared light. This point applies to fourth and fifth embodimentsdescribed hereinafter.

Next, a description will be given of the fourth embodiment of thepresent invention. The construction of an image capture apparatus 100according to the fourth embodiment is the same as that of the thirdembodiment. The controller 104 of the image capture apparatus 100according to the fourth embodiment is equipped with a function ofdetecting a predetermined object. The controller 104 detects thepredetermined object from image data, and performs emphasis processingon the detected object e.g. by setting a frame in an area of the object.The controller 104 causes the display section 106 to display the imagedata with an emphasized area provided in the area of the predeterminedobject. This makes it possible to present an image with high objectvisibility to the user. For example, in a case where the image captureapparatus 100 is applied to public road surveillance, it is assumed thatthe predetermined object is a vehicle's appearance, a vehicle licenseplate, a human body, a human face, etc. Although the predeterminedobject is assumed to be a moving object, the predetermined object may bea still object. When halation is caused in image data of an imagecaptured by the image capture apparatus 100, e.g. due to the headlightsof a vehicle, the visibility of the predetermined object is reduced. Theimage capture apparatus 100 according to the second embodiment performscontrol for detecting the predetermined object included in the imagedata, and causing the area of the predetermined object to be displayedin an emphasized manner. This improves user-friendliness.

FIG. 12 is a flowchart of a process performed in the fourth embodiment.Since steps S601 to S612 are the same as the steps S301 to S312 in thethird embodiment, description thereof is omitted. The controller 104refers to the immediately preceding image data (immediately precedingframe) temporarily stored in the auxiliary storage device 102. Then, thecontroller 104 detects a movement vector by comparing the immediatelypreceding frame and the current frame (acquired image data) which aredifferent in time (S613). A desired method can be applied to a movementvector detection method. As the movement vector detection method, forexample, the optical flow method or the block matching method can beapplied. In a case where these movement vector detection methods areapplied, the controller 104 divides the image data items into smallareas, searches for small areas having the same pixel values between theimage data items, and associates the small areas with each other, tothereby detect a distance and a direction between the small areas.

The controller 104 assumes a magnitude of the movement vector obtainedin the step S613 as an amount of blur caused by capturing an image ofthe moving object, and derives a third shutter speed for suppressingmovement blur according to the magnitude of the movement vector. Then,the controller 104 sets the derived third shutter speed (S614). Thethird shutter speed can be derived from the following equation (3):

$\begin{matrix}{S_{3} = {\frac{f_{r}}{v}n}} & (3)\end{matrix}$

In the above equation (3), “S₃” represents the third shutter speed,“f_(r)” represents a frame rate used in deriving the third shutterspeed, and “v” represents the detected movement vector. Further, “n”represents an allowable parameter.

The controller 104 derives an irradiation light amount (third lightamount) of the illumination section 103 with respect to the exposureamount changed due to controlling the shutter speed in the step S614.Due to setting the shutter speed to the third shutter speed in the stepS614, the exposure amount is reduced. The third light amount is a lightamount at which the correct exposure of the moving area is achievedagain. Then, the controller 104 performs control for setting the derivedthird light amount as the irradiation light amount of the illuminationsection 103 and causing the third light amount of infrared light to beirradiated from the illumination section 103 (S615). The third lightamount is derived by the following equation (4):l ₃ =m _(hal){1−exp(−r|d _(ev)|)}(l _(max) −l _(pre))+l _(pre)  (4)

In the above equation (4), “l₃” represents a third irradiation lightamount for achieving the correct exposure of the moving object which hasbeen darkened due to the increased shutter speed. “m_(hal)” represents amask parameter indicative of a result of the determination of halation,and takes a value of 0 or 1. “r” represents an adjustment parameter setby taking a reflectance of the object into account and takes a valueequal to or larger than 0. “d_(ev)” represents a difference in exposureamount caused by a change in the exposure amount. “l_(pre)” representsthe immediately preceding light amount. The allowable parameter “n” maybe a value properly set according to a scene to be shot, or it may be apreset value set independently of the scene. “l_(pre)” represents thesecond light amount if halation has occurred in image data, andrepresents the first light amount if halation has not occurred in imagedata.

The controller 104 performs proper image quality correction of the imagedata for further enhancing the detection accuracy of the predeterminedobject (S616). The controller 104 detects the predetermined object fromthe image data having been subjected to the image quality correction inthe step S616 (S617). The controller 104 performs control for addingdetection data to the current image data and transmitting the image datawith the detection data from the auxiliary storage device 102 to thedisplay section 106 via the data communication section 105 (S618). Thedetection data (hereinafter referred to as the “label data”) indicatesan image capture area of a target to be detected and what the target tobe detected is (type of the target to be detected). For example, whenthe object to be detected is a vehicle license plate, a label dataindicative of the vehicle license plate is added to the image data asdetection data. When the display section 106 displays the image data,the controller 104 performs control for causing the display section 106to display not only a frame of the image capture area of the target tobe detected but also the label data. With this control, the frame isdisplayed in an area of the predetermined object, which is the target tobe detected from the image, whereby the detected predetermined object isdisplayed on the display section 106 with emphasis. Further, the dataindicating what the detected predetermined object is displayed on thedisplay section 106. This makes it possible for the user to moreexcellently view the object of the image data.

Next, a description will be given of the fifth embodiment of theinvention. FIG. 13 is a block diagram of an image capture apparatus 700according to the fifth embodiment. The image capture apparatus 700 inFIG. 13 is different from the image capture apparatus 100 in FIG. 7 inthat the image capture apparatus 700 further includes an externalstorage device 707, a timer 708, and an operation section 709. The othercomponents of the image capture apparatus 700 are configured similar tothose of the image capture apparatus 100 in FIG. 7, and hencedescription thereof is omitted. A controller 704 has a function ofdetecting the predetermined object, which is described in the fourthembodiment. Further, the controller 704 causes the external storagedevice 707 to store not only label data indicating what a detectedobject is but also time information indicating a time point of detectionof the object in association with the label data.

For example, in a case where the image capture apparatus 700 is appliedto public road surveillance, image data obtained by the image captureapparatus 700 can be used e.g. for inspection as well. In this case, theimage capture apparatus 700 performs control for causing image dataobtained by capturing an object to be stored in the external storagedevice 707. Since this makes it possible not only to search for theimage data from the external storage device 707 but also to analyze theimage data, user-friendliness is improved. Here, when analysis of theimage data stored in the external storage device 707 is performed, thereis a case where all the image data stored in the external storage device707 is not necessarily required to be used. Data required for theanalysis of the image data sometimes includes image data showing adetected object, label data of the detected object, information of timeat which the image data is detected, and so forth.

Therefore, when an object is detected in the step S617 in FIG. 12, thecontroller 704 accesses the timer 708 via a data communication section705. Current time information is obtained from the timer 708. Thecontroller 704 causes the current time (time point at which an image ofthe object was captured) acquired from the timer 708 to be stored in theexternal storage device 707 in association with the image data obtainedby image capture and the label data. With this, the image data, thelabel data, and the time information are stored in the external storagedevice 707 in association with each other. The image capture apparatus700 includes the operation section 709. When the user searches for theimage data from image data items stored in the external storage device707 by operating the operation section 709, the user can perform thesearch by designating the time information. This makes it possible forthe user to easily search for desired image data.

The image data (image data on the predetermined object) found by thesearch is displayed on a display section 706. Further, by operating theoperation section 709, the user can transmit a command to the datacommunication section 705. The data communication section 705 inputs thereceived command to the controller 704. Since this makes it possible tosequentially control a photographing section 701 and an illuminationsection 703, the user can perform image capture under more appropriateconditions. Although in the fifth embodiment, the description is givenof the example in which the image data, the label data, and the timeinformation are stored in the external storage device 707 in associationwith each other, the image data and the time information may be storedin the external storage device 707 in association with each other.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2018-238628, filed Dec. 20, 2018, and No. 2018-238629, filed Dec. 20,2018 which are hereby incorporated by reference herein in theirentirety.

What is claimed is:
 1. An electronic apparatus including at least oneprocessor or circuit configured to perform the operations of thefollowing units: an evaluation unit configured to evaluate a luminanceof an object based on an exposure level at which image information ofthe object is acquired; and a detection unit configured to detecthalation based on the luminance of the object, a first luminance areahaving a higher luminance than a first luminance threshold value, and adistribution status of another luminance area which is an area having alower luminance than the first luminance area and is distributed aroundthe first luminance area.
 2. The electronic apparatus according to claim1, wherein the at least one processor or circuit is configured tofurther perform the operations of: a classification unit configured toclassify luminance areas including the first luminance area and theother luminance area, using at least one luminance threshold value; anda change unit configured to change the at least one luminance thresholdvalue according to the luminance of the object.
 3. The electronicapparatus according to claim 2, wherein in a case where the luminance ofthe object is equal to or higher than a predetermined luminance value,the change unit is further configured to increase the at least oneluminance threshold value.
 4. The electronic apparatus according toclaim 1, wherein in a case where the detection unit detects the firstluminance area and the another luminance area whose luminance becomeslower in an outer peripheral direction from the first luminance area,the detection unit is further configured to detect the halation.
 5. Theelectronic apparatus according to claim 1, wherein the at least oneprocessor or circuit is configured to further perform the operation ofan exposure control unit configured to control an exposure level of animage sensor, and wherein the evaluation unit is further configured toevaluate the luminance of the object and a luminance of ambient lightbased on the exposure level controlled by the exposure control unit. 6.The electronic apparatus according to claim 5, wherein in a case where aluminance ratio between the luminance of the ambient light and theluminance of the object is equal to or smaller than a predeterminedvalue, the detection unit is further configured to detect the halationbased also on a distribution status of a third luminance area which isdistributed around the second luminance area.
 7. The electronicapparatus according to claim 1, wherein the detection unit is furtherconfigured to detect the halation with respect to a moving one ofobjects in the image information, but not detect the halation from anon-moving one of the objects.
 8. The electronic apparatus according toclaim 1, wherein the electronic apparatus is an image capture apparatusincluding an image capture device.
 9. A control apparatus that performscommunication with an electronic apparatus, the electronic apparatuscomprising at least one processor or circuit configured to perform theoperations of the following units: an evaluation unit configured toevaluate a luminance of an object based on an exposure level at whichimage information of the object is acquired; and a detection unitconfigured to detect halation based on the luminance of the object, afirst luminance area having a higher luminance than a first luminancethreshold value, and a distribution status of another luminance areawhich is an area having a lower luminance than the first luminance areaand is distributed around the first luminance area, and the controlapparatus comprising at least one another processor or another circuitconfigured to perform the operations of the following units: anacquisition unit configured to acquire image information from theelectronic apparatus in a case where the electronic apparatus detectshalation; and a control unit configured to control an irradiationapparatus to increase the amount of light irradiated by the irradiationapparatus based on luminance information of the image informationacquired by the acquisition unit.
 10. An image capture apparatusincluding: a control apparatus; at least one processor or circuitconfigured to perform the operations of the following units: anevaluation unit configured to evaluate a luminance of an object based onan exposure level at which image information of the object is acquired;and a detection unit configured to detect halation based on theluminance of the object, a first luminance area having a higherluminance than a first luminance threshold value, and a distributionstatus of another luminance area which is an area having a lowerluminance than the first luminance area and is distributed around thefirst luminance area; and an image capture device that receives incidentlight containing infrared wavelength light, wherein the controlapparatus comprises at least one another processor or another circuitconfigured to perform the operations of the following units: anacquisition unit configured to acquire image information from theelectronic apparatus in a case where the electronic apparatus detectshalation; and a control unit configured to control an irradiationapparatus to increase the amount of light irradiated by the irradiationapparatus based on luminance information of the image informationacquired by the acquisition unit.
 11. The image capture apparatusaccording to claim 10, wherein the incident light is light of whichvisible light is cut by a visible light cut filter.
 12. The imagecapture apparatus according to claim 10, wherein the control unit isfurther configured to detect a case where a first luminance area havinga higher luminance than a first luminance threshold value exists in theimage information, and also a second luminance area having a higherluminance than a second luminance threshold value lower than the firstluminance threshold value exists around the first luminance area, as astate where the halation has occurred.
 13. The image capture apparatusaccording to claim 12, wherein the second luminance threshold value is athreshold value for determining a luminance area associated with chargeleakage caused by halation.
 14. The image capture apparatus according toclaim 10, wherein the control unit is further configured to performcontrol for detecting a moving area based on the image information, andperforming photometry on the detected moving area.
 15. The image captureapparatus according to claim 14, wherein when the halation has beendetected, the control unit is further configured to perform control forsetting a second shutter speed such that exposure is adjusted to themoving area.
 16. The image capture apparatus according to claim 10,wherein the control unit is further configured to perform processing forchanging a γ curve according to a state of a luminance histogram orprocessing for changing saturation according to a value as an index ofbrightness, on the image information acquired when the irradiation lightamount of light irradiated by the irradiation apparatus was increased.17. The image capture apparatus according to claim 15, wherein thecontrol unit is further configured to detect a movement vector based onthe image information, changes the second shutter speed to a thirdshutter speed according to a magnitude of the detected movement vector,and control the irradiation light amount of light irradiated by theirradiation apparatus such that the exposure is adjusted to the movingarea.
 18. The image capture apparatus according to claim 10, wherein thecontrol unit is further configured to detect a predetermined object fromthe image information, and perform emphasis processing on the detectedpredetermined object.
 19. The image capture apparatus according to claim18, wherein the control unit is further configured to perform processingfor causing a frame to be displayed on an area of the predeterminedobject as the emphasis processing.
 20. The image capture apparatusaccording to claim 18, wherein the control unit is further configured toperform control for adding detection information indicative of a type ofthe detected predetermined object to the image information, and causingthe detection information to be displayed together with imageinformation.
 21. The image capture apparatus according to claim 18,wherein the control unit is further configured to perform control forcausing time information indicative of a time point at which thepredetermined object was detected to be stored in a storage unit inassociation with the image information.
 22. A method of controlling anelectronic apparatus, comprising: evaluating a luminance of an objectbased on an exposure level at which image information of the object isacquired; and detecting halation based on the luminance of the object, afirst luminance area having a higher luminance than a first luminancethreshold value, and a distribution status of another luminance areawhich is an area having a lower luminance than the first luminance areaand is distributed around the first luminance area.
 23. A method ofcontrolling a control apparatus and an electronic apparatus, the controlapparatus and the electronic apparatus communicating with each other,the method comprising: causing the electronic apparatus to: evaluate aluminance of an object based on an exposure level at which imageinformation of the object is acquired; and detect halation based on theluminance of the object, a first luminance area having a higherluminance than a first luminance threshold value, and a distributionstatus of another luminance area which is an area having a lowerluminance than the first luminance area and is distributed around thefirst luminance area; and causing the control apparatus to: acquireimage information from the electronic apparatus in a case where theelectronic apparatus detects halation; and control an irradiationapparatus to increase the amount of light irradiated by the irradiationapparatus based on luminance information of the acquired imageinformation.
 24. A non-transitory computer-readable storage mediumstoring a computer-executable program for executing a method ofcontrolling an electronic apparatus, wherein the method comprises:evaluating a luminance of an object based on an exposure level at whichimage information of the object is acquired; and detecting halationbased on the luminance of the object, a first luminance area having ahigher luminance than a first luminance threshold value, and adistribution status of another luminance area which is an area having alower luminance than the first luminance area and is distributed aroundthe first luminance area.
 25. A non-transitory computer-readable storagemedium storing a computer-executable program for executing a method ofcontrolling a control apparatus and an electronic apparatus, the controlapparatus and the electronic apparatus communicating with each other,wherein the method comprises: causing the electronic apparatus to:evaluate a luminance of an object based on an exposure level at whichimage information of the object is acquired; and detect halation basedon the luminance of the object, a first luminance area having a higherluminance than a first luminance threshold value, and a distributionstatus of another luminance area which is an area having a lowerluminance than the first luminance area and is distributed around thefirst luminance area; and causing the control apparatus to: acquireimage information from the electronic apparatus in a case where theelectronic apparatus detects halation; and control an irradiationapparatus to increase the amount of light irradiated by the irradiationapparatus based on luminance information of the acquired imageinformation.